Tough call, but I don't think I would :) There are so many other great (OSS) projects that doesn't use PHP...
I am ready to bet that working on 99.9% of those open-source projects won't have the same positive impact than making Wikipedia 1% better.
I would choose Wikipedia.
you are right about the positive impact for sure, but for me it would just bring too much misery working with technology i really don't enjoy. :) If they'd ever need skills I have, I'll be happy to help :)
Maybe it's time for wikipedia to become more technology agnostic. Think more in line of a microservice architecture. At first glance it looks pretty monolithic
I mean, I guess that the pay is pretty good at Wikipedia, no? So you could work on the impactful things during 3-4 days a week, and on the interesting tech things for the rest of the week.
And also once you are there you are smart, so will find smart ways to improve their architecture, nothing is fixed in stone.
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